[time-nuts] Time Dilation tinkering

Magnus Danielson magnus at rubidium.dyndns.org
Wed Mar 22 13:45:32 EDT 2017


On 03/22/2017 12:02 AM, Tom Van Baak wrote:
> Scott McGrath wrote:
>> Or perhaps use the Symmetricom CSAC ...
> Chris Albertson wrote:
>> Get a weather balloon.  Or there might already be an amateur group that
>> launches these.  Balloons can go much higher than your local mountains.
> You'll both be interested to hear that CSAC+balloon was proposed for the "Genius by Stephen Hawking" TV program and, yes, we were in touch with amateur high altitude balloon groups. The producer rightly thought that a small atomic clock going up in a helium balloon would make dramatic video for a time dilation demonstration. Symmetricom / Microsemi donated a SA.* series clock to the effort.
> I got involved on the science and engineering side of the equation. Spent a month trying to make it work and in the end the balloon idea was dropped. Just too hard, and too uncertain, and would require many more months of R&D, and finger crossing. So that's why, instead, I drove six calibrated 5071A down to Tucson for a conventional mountain-valley time dilation experiment -- which I knew from prior experience would work, especially with 3x redundancy. http://leapsecond.com/great2016a/
> Note that miniature Rb and Cs clocks (such as those sold by Microsemi) are very small, ultra light, and amazingly low power -- but their long-term stability (including environmental effects) is a hundred or even a thousand times worse than a 5071A/001. This is not to say CSAC are poor clocks. In fact they have a superb mass/power/size to adev ratio, and thus there are many unique applications for them. But they are not designed to be laboratory-quality frequency standards

Indeed. CSAC is a superb clock for the power it consumes, and that is 
the market segment it attempts to address. For the same size and more 
power, you get much better stability. Just because it has Cesium doesn't 
make it a laboratory clock, it's a small gas-cell, with all the issues 
of one.

Which reminds me, I got three CSACs to measure. Into the lab I go.


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